Recently, secondary batteries, which can be charged and discharged, have been widely used as energy sources for wireless mobile devices. Secondary batteries have also attracted considerable attention as power sources for electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (Plug-in HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles that use fossil fuels.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle or large-sized devices such as vehicles use a battery module having a number of battery cells electrically connected to each other because high power and large capacity are necessary for the middle or large-sized devices.
Since the battery module is preferably manufactured to have as small a size and weight as possible, prismatic batteries or pouch-shaped batteries, which can be stacked with high integration and have a small weight to capacity ratio, are usually used as battery cells of middle or large-sized battery modules. In particular, much interest is currently focused on pouch-shaped batteries, which use an aluminum laminate sheet as a sheathing member, due to their advantages of being lightweight and cheap to manufacture.
Since a battery module is made up by combining a number of battery cells, safety and operating efficiency of the battery module are considerably deteriorated when overvoltage, overcurrent or overheat occurs at some of the battery cells. Therefore, it is necessary to provide a unit to sense and control such overvoltage, overcurrent or overheat. Thus, measuring members such as voltage measuring members and temperature measuring members are connected to the battery cells to check and control operating states of the battery cells in real time or at predetermined intervals. However, installation or connection of such measuring members greatly complicates the process of assembling the battery module and may cause a short circuit due to use of many wires.
In this regard, referring to FIG. 11, a conventional battery pack is configured such that voltage measuring members and temperature measuring members are connected to a connector (CNT) and a battery management system (BMS) via wiring harnesses and a temperature measuring circuit is formed along a voltage measuring circuit.
However, such a battery pack structure has a problem in that the insulation resistance of the voltage measuring circuit is reduced as an electrical connection is formed between the voltage and temperature measuring circuits by water. Another problem is that temperature measurements may change, with the result that it is not possible to correctly measure voltage and temperature.
In addition, when a battery module is constructed using a plurality of battery cells or is constructed using a plurality of unit modules, each including a specific number of battery cells, it is generally necessary to provide a large number of members for mechanical coupling and electrical connection between the battery cells or the unit modules and therefore the process of assembling such members is very complicated. Furthermore, spaces for coupling, welding, or soldering of the members are needed to achieve such mechanical coupling and electrical connection, thereby increasing overall system size. Such size increase is undesirable as previously described. Accordingly, there is a high necessity for a battery module which is more compact and exhibits high structural stability and which is also capable of correctly measuring temperature and voltage.